Pebble heating chamber



April 15, 1952 s. P. ROBINSON 2,593,345

PEBBLE HEATING CHAMBER Filed July 20, 1948 2 smug-swam 1 INVENTORJ S. P. ROBINSON s w y y A T TORNE Y6" April 15, 1952 s. P. ROBINSON 2,593,345

PEBBLE HEATING CHAMBER Filed July 20, 1948 2 SHEET SHEE 2 F762 FIGS INVENTOR.

.P. ROBINSON BY i A T TOR NE KS Patented Apr. 15, 1952 PEBBLE HEATING CHAMBER Sam P. Robinson, Bartlesville, kla., assignor to Phillips Petroleum Company, a corporation of Delaware Application July 20, 1948, Serial No. 39,709

6 Claims. 1

This invention relates to an apparatus for heating pebbles. pects, it relates to an improved apparatus for heating a contiguous moving mass of pebbles.

Many processes used in industry today, particularly those wherein the constituents are gaseous, require high temperatures to enable them to operate at maximum efiiciency or to be operable at all. Several diiierent types of apparatus have been used with varying success. One particular type highly suited to heating gases to such temperatures as 2000 to 3000 F. or of course, to lower temperatures, is the pebble heater. Generally, this apparatus is constructed primarily of refractory bricks contained within an outer metal shell. The construction is such that a contiguous mass of pebbles may be passed through and exposed to hot gases. The design is made so that the pebbles will pass through the heater in an even flow, that is, the pebblesat the side of the chamber pass through at the same rate as those toward the center; and so the pebbles will be evenly heated. Some of the processes which may utilize a pebble heater to particular advantage, to name just a few, are cracking of hydrocarbons, synthesis gas (H2 plus CO) generation, and super-heating of steam.

In most processes using pebble heaters, the pebbles are first heated in a conventional heater and then passed by gravity, utilizing suitable control apparatus, to a reaction chamber situated below the heater. The material, or materials, to be heated are introduced to this chamber under suitable pressure conditions so that there will be no flow of hot gases from the heater to the reaction chamber, and only a slight flow of reactants" into the heater. By so controlling the pressure, the materials within the reaction chamber remain uncontaminated. The speed of pebbles which flow in a contiguous mass through the heater and the reaction chamber is controlled to give the desired temperature within the reaction chamber.

The term pebbles as used herein refers to refractory elements which form a fluent, particulate mass. These pebbles are preferably substantially spherical and relatively uniform in size, but may be rod shaped or irregular in shape or size. Spheres of about A; inch to 1 inch in diameter are suitable and those of inch to /2 inch diameter are preferred. Care must be taken to select pebbles of proper composition for a given process. In cracking organic materials at elevated temperatures, pebbles of highly refractory character and ruggedness must be uti- In one of its more specific aslized. In conducting endothermic reactions at elevated temperatures, it is important to operate with pebbles of relatively high specific heat in order to introduce sufiicient heat to the conversion chamber with a minimum flow of pebbles. Pure alumina pebbles fired at temperatures between 3000 and 3500 F. are suitable for many hydrocarbon conversion processes. Pebbles comprising beryllia, silicon carbide, mullite, periclase, and zirconia make excellent contact materials for some processes. Pebbles of the materials above named may be impregnated with other materials which are catalytic in nature, but this treatment usually renders them less suitable for use at extremely high temperatures such as 2500 F. and higher. Metal balls such as nickel, monel, inconel, iron, copper, etc., have utility in specific processes. Various adsorbent materials such as silica gel, active aluminas, activated carbon, etc., have wide utility in gas treatment and adsorption.

An object of this invention is to provide an apparatus for contacting gases and solids in countercurrent flow which permits substantially uniform contact time throughout the bed of solids.

Another object of this invention is to provide a gas-solid contact chamber in which hot gases are generated therein.

Another object of the invention is to provide apparatus for contacting gases and pebbles which assures substantially even distribution of gases throughout the mass of pebbles.

Another object is to provide apparatus for contacting hot gases and pebbles which includes a tempering bed to insure a more even temperature throughout the mass of pebbles.

Another object is to provide an apparatus for uniformly heating a mass of pebbles in which is located a hot gas generating chamber supported from the top of the pebble heater by hollow supporting members through which may be circulated a suitable coolant.

' Another object of this invention is to provide top'of an annular space formed betweenthe in her surface of the pebble heater shell-and the outer surface of the heat-generating chamber which is axially positioned within the pebble heater. The heat-generating chamber is formed by hard-burned abrasion-resistant brick and 4 line 2--2 which shows the positioning of the pebble inlets and the heat generating chamber. Figure 3 is a horizontal cross-section also of the pebble heater shown in Figure 1 taken along burner tile built around and supported by metal line 3'3 and shows the manifold for passing pipes attached to a nose ring and through which coolant through the supports for the heat genis circulated a suitable coolant. In addition the crating chamber. Figure 4 is an enlarged cut chamber'is supported from the top of the pebble .away isometric view of a portion of the nose ring chamber by the metal pipes. The arrangement of the heat generating chamber shown in Fig- 7 of the brick and tile is such that a minimum of ure 1 which shows one method for suspending gas will pass therethrough. Examples ofsuch the abrasion resistant brick and burner tile on construction are shown in the attached drawings M the nosed ring and around the vertical piping which are discussed below. However, these which supports the nose ring. Figure 5 is a drawings should not be interpreted as limiting --vertica1 cross-section of Figure 4 taken along the scope of my invention, but rather as parline 5 5 and shows again the way in which the ticular examples of it. In a preferred emboditile and brick are suspended on the nose ring. ment of this invention, the heat-generating I Figures 6 and 7 show two examples of brick and chamber extends through the top of the pebble tile construction which may be used to prevent heater shell, although it is within the scope of gas passage through the heat generating chammy invention to have this chamber extend from her. the top' of the-shell orto be located entirely withi Refer'to Figure l'which is a vertical cross sec- -in;sai d-'shell; "Within the broad" aspect of my =tion -ofone em-bodiment of my .apparatush- Nuinvention; the heat-generating chamber may be meral l0 indicatesthe outer shell of' the-pebble supported by means other than the metal-pipes heater. which includes a vertical shell-closed at described above, such as solid metal rods or other "ieitherend, the top I l of said shell bein in the suitable means. However, when utilizing my ap- :shape-oia-dome and the bottom l5 of said (shell paratus to heat pebbles to the high temperatures being in the-shape of a frustum, of an invertfiwithin thescope of myinvention, it is preferred Ledcone wherein the angle of convergence of the to use hollow pipes of one type or another 'sides is preferably less than Number I2 rrthrough which maybe circulated a suitable 'cool- Bot-indicates the pebble throat. Number l3 indicates gent; In -any modification ofmy. invention, the the"v heat-generating. chamber which extends 1' n:heat-generatingchamber should be axially posithrough the top dome of the shell. tionedand supported by or from the top of the Numberhi is the metal outsidestructural'supjshell so that the lower open end thereof forms a port of the. heater. Numb-er l6 is'therhardrelatively-narrowannularspace between said 35 burned abrasion-resistant ceramic brick insulate'nd'and the=wa11 of the frustro-conical lower pop. ingiilining of the vertical shell, frusto-conical 131011 -of the-pebble heater shell. This-arrangesection,'iand :pebble throat; .rNumeral'll is the A'-ment provides more'uniform heating of the pebinsu ati g cement port of the 17 1 Of the p l blesgwith 'maximum efiiciency.- Asthe pebbles r a heater.

- -pass-downward in a contiguous mass they are to -Number '26 is a p p introducing Co heated by radiation and conduction through the .z material' to manifold 25 from which it :-passes "walls'oi the'heat-generating chamber-as well as mthrough pip s 23 t0 n se r ng 2 Number 21 are" by; the'hotgases which pass through them in v outlet pipes :whichcarry the cooling material counter-current-flow. ,1 from, the nose; ring to manifold 2D.v from -which The-portion of the pebble heater which extends iit is removed throu pipe It vITlOWeVeI, below the -mouth of the heat-generatin cham- Within t e c p of t s ihve ien 1103' lie/SS the her is ate peringarea or bed whe e the pebbles coolant inopposite directions to that indicated are allowed t remain sumciently 1 fox; th .7 as may be desirable under certain conditions, temperature to became relatively even t :particularly if the cross-section area of the inout. Frornthe tempering bed the'pebbes pass ner pipe is greater than thecross-section of the through what is known as a pebble throat 1o- 5 nular space between the inner and outer pipegated -31; th bottgm of t temperingbed and Number 2'l.is a ring of hard-burned abrasionfr m the teto Whatever use ibis desiredto make resistant :bricks so fashioned that the bricks northern. .:completely encompass the 'nose ring and are Amodiiicatiomof my invention is to introduce -'supp0rted by same as shown in Figuresv 5;and 7 hot gases such as'refinery flue gases into the 0f thisspecification discussed below: Number h ateneratin chamber, In any case; the hot ii 28' indicates burner. tile which'are so. arranged ;-gasesgenerated within or without the pebble e5 form t ef 0 y of heat gel'leratingchamber .7 heaterfalvepassed downward through the heat; l3.'- Thesetile are so'constructed that: they fit generating Chamber and t t pen lower end --.,around tubes 2! to -protectfthem from .direct into the gas space formed by said'end' and the -heafi. NumberZQindicates a Venturitubein the pebble bed thereunder. The gases pass from the burner thr the e at tcham er gas space upwardly through the pebblesrand int Which aids in mixing the combustion-materials. another gas space located just below the top f vgNumber 30 indicates insulating brick which close thepebble heater shell. From here, they are 1 the'upper end of the'heetegenerefifigChamber removed by suitable means such as one or more and through which extends burner 3| to-"which ilues.

A further understanding of some of the many aspects of my invention may be had by-referring is attached nozzle 35. Numeral 32 indicates a pair offlang-es bolted together so thatthe burner V and-nozzle may be removed for cleaning or reto: the; accompanying drawings in conjunction placement; Pipes 33 'and- 34 are inlet means to j with the following discussion. burner extension 36 forfuel and air.

Figure 1 is,ayertical-cross-section ofone spe- Reservoir '31 is for pebbles to be heated;- Said cificembodiment ,of my invention partially cut V pebbles, are passed through pipes-38which pass away Figure 2. isa; horizontal cross-section of throughthe topof the heater and into" the upthe pebble heater shown in Figure 1 taken along 7 A l per portion of annular space 39 formed between heat-generating chamber l3 and the outer heater shell ID. The hot gases which are generated in chamber 13 pass out its lower end, up through the annular space, and out stack, or stacks, 40 located at the top of said annular space.

Figure 2 is a horizontal cross-section of the pebble heater shown in Figure 1 at line 22. The same parts of this drawing as are shown in Figure 1 will be similarly numbered. The metal shell supporting the pebble heater is indicated at M. Numeral I6 is the hard-burner abrasionresistant brick lining of the pebble heater. Number 38 indicates inlet pipes for pebbles to annular space 39. Number 13 indicates the heatgenerating chamber comprised of burner tile 28. Numbers 2| and 23 show outlet and inlet pipes for cooling material. Number 25 indicates the inner surface of pebble throat l2.

Figure 3 is a top view of the pebble heating chamber shown in Figure 1 taken at line 33. As in Figure 2 parts of this drawing identical to parts in Figure 1 are identified by the same number. Number l indicates the periphery of the pebble heater. Number 38 indicates the pebble inlets as previously indicated in Figures 1 and 2. Pipes 33 and 34 are inlet means'for fuel and air to burner extension 36. Pipe 26 is an inlet means for cooling material to manifold 24. Pipe I8 is a cooling material outlet means for manifold 29. Number 32 is a pair of flanges attached to burner extension 36 which is bolted to the burner flange below with bolts 42. The hot gas exhaust stack is indicated at 40.

Figure 4 is an enlarged cutaway perspective view of a portion of the nose ring of the heatgenerating chamber. As in the other drawings. those parts which correspond to identical parts shown in Figure 1 are similarly numbered. This drawing shows the assembly of thefirst row of brick at the mouth of the chamber and the means for supporting same. It also shows the arrangement of the burner tile, how they fit around the cooling pipes, and ridges and grooves for retarding the passage of hot gases through them. Number 22 is the hollow nose ring to which are attached the individual cooling members 2| which also support the chamber. These cooling members are attached by welding to the nose ring where a hole has been cut out substantially the size of the cooling pipe so that material used for cooling may be passed into the nose ring. Number 23 is the inlet cooling pipe which extends into the nose ring. Numbers 2'! and 28 are hard-burned abrasion-resistant brick and burner tile, respectively. Number 43 is a means for supporting the lower ring of brick which in turn supports the rest of the burner tile comprising the heat-generating chamber. As shown here it is an inverted channel iron, the bottom of which has been creased orbent downward sufliciently to keep the brick from falling or bein pushed off. A more clear idea of this may be had by referring to Figure which is a vertical cross-section taken at 5--5 of Figure 4. This drawing shows the design of brick 21 which are so constructed that they will fit on channel iron 43 and surround nose ring 22. Further, the more pressure applied to the top of bricks 21 the better they will fit together, be-

cause the design of the flange upon which they rest is such that the bricks tend to slide toward each other. This pressure would be that of additional layers of brick and tile forming the upper portion of the heat-generating chamber.

lizing my pebble heating apparatus.

This drawing also shows how pipe 23, which is the inlet means for the coolant, protrudes into the nose ring. Numerous coolants may be used for circulation through the pipes in the heatgenerating chamber, depending upon the temperature at which the apparatus is to be operated. Water is a very satisfactory coolant for high temperatures because of the heat it removes on vaporization. Other suitable coolants are mercury, and Dowtherm (a mixture of diphenyl and diphenyl oxide). It may also be advantageous to utilize inert gases as coolants. In general, any material will be satisfactory as a coolant if it will remove sufiicient heat, and will not decompose in the pipes leaving a deposit or react with the pipes.

Figures 6 and 7 merely give two examples of burner tile construction of the heat-generating chamber to prevent gas passage between the individual tile. Similar grooves and ridges to those shown in Figure 6 are shown also in Figure l. In both drawings, number 23 indicates one of the inlet means for cooling material and number 2| indicates one of the outlet means for cooling material.

It is within the scope of my invention to suspend the heat-generating chamber by other means than those shown in the above described drawings. For example, rather than having one pipe within the other, only one pipe may be used at each place. Thus every other pipe would pass coolant down to the nose ring through which it would pass to the next pipe on each side and be removed therethrough. Other means for suspending the heat-generating chamber through which may be circulated a suitable coolant are also within the scope of my invention.

There are many advantages attained in uti- Foremost among them are increased heat transfer capacity and thermal efficiency by having the heatgenerating chamber located within the pebble heater and reduction in over-all weight obtained by eliminating interior supports for the heatgenerating chamber. Two other important advantages are reduction in construction cost by the simplicity of the apparatus, and better performance with less maintenance required. Other specific improvements of my apparatus over the art are; no static pebble zones exist because all the walls are steeper than the angle of rest of submerged pebbles under load; all pebbles must pass through the zone exposed to hottest combustion gases; flow of pebbles to the single pebble outlet or throat is unrestricted; the pressure drop is relatively low because of less restriction to flow of the hot gases; and lessening of the requirement of thick walled insulating fire brick protection for the shell. My apparatus provides high capacity, cheap, light, and simple construction.

Although this apparatus has been described in terms of its preferred modifications, it is understood that various changes may be made without departing from the spirit and scope of the disclosure and of the claims.

I claim:

1. An apparatus for imparting heat to material, which comprises a vertical metal shell, a top member, an axially positioned heat-generating chamber constructed of burner tile supported by a bottom ring of hard-burned abrasion-resistant brick, vertical hollow members supporting said tile and said brick and enclosed within same and through which may be passed cooling material, means :for supporting said vertical hollow members from the top ofsaid shell, said chamber extending downwardly through said top member 1 and terminating in a freely-open lower end, a "ceramic brick lining for said shell, said chamber and said shell forming an annular space for containing material to be heated,a plurality of inlet :means'for introducing said material into the top of said annularspace, outlet means for said heated material in said bottom member, means 3 for causing-flow of hot gases through said heatannular space to heat said material therein and thence into said gas oulet means are exhausted.

2. An apparatus for heating a downwardly flowing contiguousmass of pebbles, which comprises a vertical shell comprising an upper cylindrical portion and a lower frusto-conical portion I and composed of at least an outer metal support and an inner ceramic brick lining, a top member for said shell, an axially positioned ceramic brick heat-generating chamber extending downwardly :through and supported by said top member and terminating in a freely open end at a point within 'said shell above the bottom thereof and below the upper limit of said frusto-conical portion and forming with said shell an annular space for containing a downwardly flowing contiguous mass of pebbles to be heated, the space within said 'frusto-conical portion below said freely open end of said heat-generating chamber comprising a tempering-zone for said pebbles, a plurality of i inlet means for introducing pebbles into said annular space, outlet means for said heated pebbles at'the bottom of said shell forming a pebble throat, means for causing flow of hot gases through said heat-generating chamber and out said'freely open end thereof into a gas space 3 created at the bottom of said chamber by said freelyopen end and said contiguous mass of pebbles, and gas outlet means leading from the top of said shell whereby said hot gases passing upwardly through said annular space to heat said pebbles therein and thence into said outlet means are removed.

3.- An apparatus for heating a downwardly flowing contiguous mass of pebbles, which comprisesa vertical steel'shell, the bottom member of said shell forming a frustum of an inverted cone, the top member of said shell forming a dome, said dome being lined with insulating concrete, an -;axially positioned heat-generating chamber constructed of burner tile supported by a bottom :ring of hard-burned abrasion-resistant brick, said tile and brick being fabricated so as 'to inhibitthe-passage of gas therethrough, and hollow members enclosed within said title and brick and supporting same through which may "be passed cooling material, said chamber extending downwardly through and supported by said top member and terminating in a freely open lower end ata point within said shell and above the bottom of and substantially below the upper limit of said frustum, a ceramic brick lining for said shell, said chamber and said shell forming an annular space for containing a downwardly "fiowing'contiguous mass of pebbles to be heated,

the space within said frustum of an inverted cone extending below said freely open endofjsaid heat-generating chamber comprising a-tempering zone of said pebbles, a plurality. of inlet. means for introducing pebbles into the .top' of .said an nular space concentrically positioned to provide a uniform contiguous mass of pebbles withinsaid annular space, outlet means for said heated pebbles at the lower end of said bottom member forming a pebble throat, meansfor. causing flow of hot gases through said heat-generatingchamher and out said freely open end. thereof into a gas space created at the bottom of said chamber by said freely-open end and said contiguous mass of pebbles, and gas outlet means leadingfrom the top of said shell whereby said hot gasespassing upwardly through said annular 'space to heat said contiguous mass of pebbles. therein and thence into saidgas outlet means are removed.

4. An apparatus according to claim-2 wherein said plurality of inlet means for. said pebbles to said annular space are concentricallypositioned in relation to said heat-generating chambeizand said vertical shell, and centrallylocated between said chamber and said shell.

5. An apparatus according to claim 2 wherein the angle of convergence of thesides of said frusto-conical portion is lessthan 60 degrees.

6. An apparatus according toclaim 3.wherein said heat-generating chamberis cylindrical and comprises a burner throat at the upper end thereof, inlet means to said throat through which -may be passed fuel and air, a horizontal hollow supporting nose ring member, a plurality of .vertically positioned hollow members radially positioned aboutthe axis of said chamber and spaced 1 equidistant from each other and-each: comprising two concentric hollow members, said,, vertical members supporting said nose ring and being attached to same in such a manner. that a coolant -may' be passed downwardly throughthe. inner members into said nose ring and upwardly through the outer members, means for introducing a coolant to said inner members, means for withdrawing said coolant from saidouter members, hard-burned abrasion-resistant bricksrsupported by andenclosing said nose ring, burner tile forming the body of said heat-generating chamber and enclosing said vertically positioned hollow members, and means for supporting said vertically positioned hollow members.

' SAM P. ROBINSON.

- REFERENCES CITED The following references are of .record in: the file of this patent:

UNITED STATES PATENTS Number a Name .-Date' 1,566,608 Kruse Dec. 22, 1925 1,953,858 Gregor Apr. 3, 1934 2,201,738 Neve May 21, .1940 2,445,554 Bergstrom July 20,1948 2,446,805 j Bergstrom Aug. 10,1948 2,460,085 r Hess a Jan..25,1l949 2,499,624 'Bergstrom et a1. Marni, 1950 FOREIGN PATENTS Number Country x-Date 828,944 France Mar. 7, v1938 

1. AN APPARATUS FOR IMPARTING HEAT TO MATERIAL, WHICH COMPRISES A VERTICAL METAL SHELL, A TOP MEMBER AXIALLY POSITIONED HEAT-GENERATING CHAMBER CONSTRUCTED OF BURNER TILE SUPPORTED BY A BOTTOM RING OF HARD-BURNED ABRASION-RESISTANT BRICK, VERTICAL HOLLOW MEMBERS SUPPORTING SAID TILE AND SAID BRICK AND ENCLOSED WITHIN SAME AND THROUGH WHICH MAY BE PASSED COOLING MATERIAL, MEANS FOR SUPPORTING SAID VERTICAL HOLLOW MEMBERS FROM THE TOP OF SAID SHELL, SAID CHAMBER EXTENDING DOWWARDLY THROUGH SAID TOP MEMBERS AND TERMINATING IN A FREELY OPEN LOWER END, A CERAMIC BRICK LINING FOR SAID SHELL, SAID CHAMBER AND SAID SHELL FORMING AN ANNULAR SPACE FOR CONTAINING MATERIAL TO BE HEATED, A PLURALITY OF INLET MEANS FOR INTRODUCING SAID MATERIAL INTO THE TOP OF SAID ANNULAR SPACE, OUTLET MEANS FOR SAID HEATED MATERIAL IN SAID BOTTOM MEMBER, MEANS FOR CAUSING FLOW OF HOT GASES THROUGH SAID HEAT- 